Correct option is C
Given:
A : B = 2 : 3
B : C = 2 : 3
C : D = 3 : 4
Solution:
A : B = 2 : 3
B : C = 2 : 3
Make B equal in both
LCM of 3 and 2 = 6
So rewrite:
A : B = 4 : 6
B : C = 6 : 9
So A : B : C = 4 : 6 : 9
C : D = 3 : 4
C = 9 in previous ratio, so scale to match
Multiply C : D = 3 : 4 by 3
C : D = 9 : 12
So A : B : C : D = 4 : 6 : 9 : 12
A : D = 4 : 12 = 1 : 3